The reality of hybrids

We put BMW's ActiveHybrid 3 and its 320i sibling through the real-world wringer to determine the benefits of electric assistance.

April 4 2013

Sam Hall

The BMW ActiveHybrid 3 vs BMW 320i.

The BMW ActiveHybrid 3 vs BMW 320i.

The BMW ActiveHybrid 3 vs BMW 320i.

BMW ActiveHybrid 3.

BMW ActiveHybrid 3.

BMW ActiveHybrid 3.

BMW ActiveHybrid 3.

BMW ActiveHybrid 3.

BMW ActiveHybrid 3.

BMW ActiveHybrid 3.

BMW ActiveHybrid 3.

BMW 320i.

BMW 320i.

BMW 320i.

BMW 320i.

BMW 320i.

BMW 320i.

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Hybrids, once the domain of hippies and green-conscious businesses, have now become an object of greed.

The purists will disagree, but in a bid to give motorists more bang for their buck, as well as reduce emissions, car manufacturers are now teaming electric and petrol to boost performance.

The use of hybrid technology in sports cars isn't new. Lexus has been spruiking “guilt-free motoring” in its sports sedan range ever since the release of the GS450h in 2005, and hybrid technology is now creeping into some of the world's fastest supercars, with the likes of McLaren and Ferrari producing electric-assisted hypercars.

A major stigma attached to sporty hybrids is that the electric motor component exists only to enhance the performance produced by the internal combustion engine.

In a bid to challenge that convention, Drive conducted a fuel-efficiency showdown: assessing whether an electric motor makes any real impact on overall fuel use, and if so under what sort of driving conditions.

BMW is a fashionably late arrival to the hybrid party in Australia, launching its ActiveHybrid 3 earlier this year. It is a mining magnate masquerading as a greenie; essentially a guilt-less version of its menacing 335i that combines a 40kW electric motor with its 3.0-litre turbocharged six-cylinder engine.

A recent Drive review concluded that the hybrid, with its 250kW of power and 450Nm of torque, isn't the fuel miser that BMW claims. The German manufacturer says the ActiveHybrid 3 sips on a miserly 5.9L/100km – an astounding figure given the car can sprint from 0-100km in 5.3 seconds.

Needless to say, our initial observations were met with some opposition from BMW, so we've pitted the hybrid against its most conventional (if you can call it that) four-cylinder car, the turbocharged 320i sedan. BMW claims the latter will consume 6.0L/100km in a mix of city and highway driving, making it a worthy opponent – on economy at least – to the ActiveHybrid 3.

We drove the cars simultaneously on the same route, and we switched between two drivers regularly to even out the difference in weights and driving styles (driving habits contribute greatly to fuel consumption). Both cars were programmed to their standard driving modes, driven in automatic and run with the air-conditioning on.

Two-thirds of the way through the test – after 55km of driving in medium density traffic including some freeways – both cars were pretty close to the money, averaging 7.5L/100km.

In the end though, following a slow crawl in stop-start city traffic, the ActiveHybrid 3 marginally won the test, averaging 7.8L/100km after almost four hours of driving at an average speed of 40.3km/h.

Comparatively, the 320i completed two laps of the same circuit with an average consumption of 8.0L/100km.

The hybrid's biggest fuel-saving benefits were in traffic and at slower speeds, where the electric motor gently intervened at lower revs and on descents. Often, this meant the petrol engine wasn't required to accelerate the car's 1655kg mass until it was already in motion.

We didn't choose to run the Hybrid on electric power only, but those settings would have almost certainly improved efficiency further. BMW claims the ActiveHybrid 3 can be driven solely on electric power at speeds of 75km/h, with a total range of 4km if you maintain a speed of 35km/h.

Where the test became interesting was an additional test loop from Sydney's CBD to Eastern Creek in the western suburbs, in which the trip computer was re-set and both cars were driven more vigorously.

Despite some enthusiastic driving through the city, the ActiveHybrid3 levelled out to an impressive 7.7L/100km in conjunction with around 20km of highway driving. Short of driving the hybrid like a racecar, there were clear benefits in having the electric motor on tap. This was illustrated particularly well when you compare the car's fuel consumption with the 335i on which it is based – which boasts a thirsty city figure of 11.1L/100km, yet weighs 145kg less and is only 0.2 seconds slower (on paper) accelerating to 100km/h.

Not surprisingly, the less powerful 320i was much more frugal than the ActiveHybrid 3 during the second test – but not by much – consuming 6.9L/100km.

The results prove firstly that BMW's claimed fuel consumption figures are difficult to achieve in everyday conditions. However, the test did shed light on the fact that you can have the power and performance of a healthy six-cylinder with the same economy of a four. And, on paper, the ActiveHybrid3 delivers stark savings over the standard 335i.

Given that the ActiveHybrid 3 is BMW's first Australian attempt at a hybrid-powered car, it seems the time has come that hybrid owners truly can have their cake and eat it, too.